I've seen a DJ with a similar cabinet here. I'm unsure as to how large drivers in small enclosures with short, small ports can constitute "subwoofers". Does anyone have an FR and distortion measurements for these things, particularly at higher volumes?

Link doesn't work for me.
Tried to search for McCauley but nothing returned.

I used the 6174 18" McCauley
in some 18 cubic feet reflex cabs (6 of them) back in the late 90's. They weighed about 250 lbs! But man, used as center fill, they were BEASTLY. They were ran 21 Hz - 30/40 Hz depending. So they acted like fans for those people right in front of them and made the people in the back want to come to the front!
If I recall correctly 95 Db 1 w/1m

Link doesn't work for me.
Tried to search for McCauley but nothing returned.

I used the 6174 18" McCauley
in some 18 cubic feet reflex cabs (6 of them) back in the late 90's. They weighed about 250 lbs! But man, used as center fill, they were BEASTLY. They were ran 21 Hz - 30/40 Hz depending. So they acted like fans for those people right in front of them and made the people in the back want to come to the front!
If I recall correctly 95 Db 1 w/1m

I've seen a DJ with a similar cabinet here. I'm unsure as to how large drivers in small enclosures with short, small ports can constitute "subwoofers". Does anyone have an FR and distortion measurements for these things, particularly at higher volumes?

I havent seen any. That would break the faith some have in their magical properties perhaps. Personally Id prefer multiple smaller woofers since huge box equals panel modes begin to appear in the usable bandwidth,which you dont want.